Change xml in those Atom, RSS, RDF how you do it ?

Hi to all,

Hi use rss feed creator and extract from mimes blogs in blogger, i saw this special link at the head

<content xmlns="http://www.w3.org/2005/Atom" type="html">
xmlns ?????


I try to extrat from site i have the only trouble sitemap is in xml and can not open it ??? they only accept Atom, RSS, RDF so is there a page online or a program who can change xml in those Atom, RSS, RDF please ???

Thanks a lot